1. Field of the Invention
The present invention relates generally to lens driving devices and, more particularly, to a lens driving device which is able to increase displacement without restriction, does not require a complex structure despite having a low power consumption, solves problems of friction and noise occurring in a gear mechanism, and realizes miniaturization and lightness, thus being easily applied to a variety of industrial fields that use optical lenses.
2. Description of the Related Art
Recently, with the development of communication technology and digital data processing technology, technology relating to portable terminals having various functions, such as data processing and calculation, communications, picture data input and output, etc., is gaining popularity. As examples, there are a PDA (portable digital assistant) which has a digital camera and a communication function, and a cellular phone which has a digital camera and a PDA function. According to the development of the digital camera technology and the data storage capacity, the installation of high performance digital camera modules is gathering strength.
Furthermore, according to the use of megapixel image sensors in digital camera modules which are installed in portable terminals, the importance of additional functions, such as auto focus and optical zoom functions, is further emphasized. In such a small digital camera module, to implement the auto focus and optical zoom functions, an actuator that occupies a relatively small volume and realizes a rapid actuating speed, low power consumption and large displacement is indispensable. In the case of a conventional magnetic actuator such as a VCM (voice coil motor), there is a technical limit in the increase in displacement, and there is a disadvantage in that power is continuously consumed while conducting a zoom function. In addition, in the case of an actuator such as a stepping motor, which rotates a lead screw in order to linearly move a movable unit, there are disadvantages of a complex mechanism and friction and noise due to a gear mechanism. Furthermore, in the case of the conventional actuators, which use the VCM motor and the stepping motor, it is difficult to manufacture the actuator at low cost and, as well, there is a limit to miniaturization.